Half perf pipe french drain - Water from above and below

[TomTheGardener]

Hi all
I am working on a garden where I am intending to pave outside the back door to a basement room. I have inherited a french drain that runs the length of the back face of the house. It comprises of a foot deep channel filled with clean chippings with a half perforated pipe running to a conventional drainage system. The perforations are set at the bottom of the pipe, the configuration for a dispersal drain. The issue I have is that as there will be run of from the paving as well as potential rising water due to the basement ground level being 10ft below normal ground level. My gut feeling is that the pipe should have the perforations on the top so if the water level gets too high it can drain into the the pipe and down to the drainage system. Can somebody advise me because if this is the case I will have to let the owner know before I proceed.
Cheers
TtheG

[lutonlagerlout]

i reckon you are right tom
even a land drain shouldnt have all the perfs at the bottom
can you not just install linear channels?
better job all round IMHO
LLL

[TomTheGardener]

i reckon you are right tom
even a land drain shouldnt have all the perfs at the bottom
can you not just install linear channels?
better job all round IMHO
LLL

I suggested that but the architect felt that a french drain was better for any rising damp. I am not sure that is the case and my feeling is that the majority of water will be run off not sub-soil moisture??